♂ Body-length 6.6-7.4 mm; wing-length 6.5-6.8 mm. Interfrontalia brownish yellow to dark brown in ground colour and whitish yellow pollinose; parafacials and cheeks brownish yellow to blackish in ground colour and whitish yellow in pollinosity; occiput blackish in ground colour, bluish grey and more or less brownish in pollinosity; antennae blackish; palpi blackish, sometimes slightly brownish at base; haustellum with mentum blackish and polished. Thorax in ground colour blackish, at most brownish along pleural margins, and rather densely covered with pale yellowish grey pollen, which is slightly tinged with blue; mesonotum more or less tinged with brown in pollinosity, when viewed from front almost darkened, and when viewed from behind with obscure median vitta and lateral patches. Abdomen blackish in ground colour, and rather densely covered with pale yellowish grey pollen, which is more or less tinged with blue; tergites when viewed from front wholly darkened, and when viewed from behind with narrow median vitta, which is not very sharp, and without fore marginal band except on 2nd tergite; prebasal sc1erite very thinly pollinose and shining; 5th sternite reddish brown to dark brown. Legs largely yellow; coxae blackish, at most partly brownish; trochanters brownish to yellowish; femora yellow, with blackish apex; tibiae yellow, more or less darkened at base and apex; tl sometimes dark yellow or brownish; tarsi blackish. Wings distinctly tinged with brownish yellow, at base strongly yellow; calyptrae strongly yellow; halteres yellow, at base more or less brownish. Head about 1.3-1.4 times as high as long; frons narrower than anterior ocellus, usually about half as wide as the latter; interfrontalia interrupted by contiguous parafrontals, with a pair of distinct if, which are usually about as long as ocellar setae; parafrontals with 3-5 ori mingled with a few or some vestigial setulae, and with no ors; As about 2-2.3 (in 1 specimen 1.8) times as long as wide; arista distinctly pubescent, the longest hairs being longer than basal diameter of arista, usually about twice as long as the latter; profrons more or less wider (in 1 specimen slightly narrower) than As; cheeks as high as or a little higher than A3-width, with genal setae in 2 rows; epistoma more or less behind frons at lunule, at most sometimes projecting forwards about as far as the frons; palpi slender, about as long as A2 and Aa combined; haustellum slender, with mentum longer than palpi. Mesonotum with 3-5 pairs of pre acr, setae of the 2nd pair being much stronger than the others and separated from each other by a distance as long as or twothirds of that between dc and acr; 1-2 setulae usually present between rows of pre acr; pra longer than or at least as long as anterior ntpl; mesopleura with 1-2 anterior mpl which are as fine as or slightly stronger than adjacent accessory setulae, and with 2 pstg and 2-8 (usually 4-7) associated setulae; stpl 1 :3, the lowest posterior being rather strong in 1 specimen, yet usually fine and only a little stronger than accessory setulae; scutellum bare on dorsal centre. Abdomen depressed except on hypopygium which is half-depressed, about 2.4-2.9 times as long as wide, and nearly parallel-sided. Fore tibia with 1 (sometimes 2) ad and 1 (sometimes 2) pv, apical pv being always strong; f2 with no distinct av, and on basal half with some (usually 4-5) pv, the longest one about 1.2-1.4 times as long as height of the femur; t2 with 1 (rarely 2) ad, 2 pd and 2-3 pv; fa with a row of strong av, the longest one being about 1.8- 2 times as long as height of the femur, and with a complete or incomplete row of weaker pv, the longest one of the setae on basal two-thirds being as long as or a little longer than height of the femur, and the longest one of the setae on apical fourth being a little or rather distinctly longer than height of the femur; t3 with 2-4 (rarely 5) av, 4 (rarely 5) ad, 3 (sometimes 4) pd and 2-7 pv, apical pd being weak or rather distinct, yet much shorter than apical d. Wings with costal thorns minute; costa haired on ventral surface; m-m only a little oblique and hardly sinuate. ♀ Body-length 6.2-7.1 mm. More yellowish than in male. Interfrontalia orange yellow on lower half and blackish on the upper in ground colour; parafacials and cheeks orange yellow in ground colour and yellow in pollinosity, which is paler on cheeks; palpi paler than in male, sometimes yellowish at base; occiput in pollinosity bluish grey and more or less yellowish. Thorax in pollinosity more yellowish than in male; mesonotum hardly tinged with brown in pollinosity, and more faintly vittate; scutellum sometimes yellowish in ground colour on ventral surface. Abdomen bluish grey and slightly yellowish in pollinosity, with tessellations in some lights; 6th tergite polished or nearly so. Coxae yellowish, or sometimes brownish and partly blackish; trochanters yellow. Wings yellowish, and hardly tinged with brown. Head only a little higher than the length, at most about 1.1 times as high as long; frons about 0.36-0.41 times as wide as head; interfrontalia about twice as wide as parafrontalia; parafrontals with 2-3 (usually 2) strong and a few fine or vestigial ori, and with 2 ors, which are strong and directed outwards; profrons about 1.3-1.4 times as wide as A3; cheeks with genal setae fewer in number (about 3-4) and much finer than those of male and nearly in 1 row. Stpl 1 :2. Mid femur on basal half with a few rather fine pv, which are shorter than height of the femur; t2 with 1 (rarely 2) ad, 2-3 pd and 2 (rarely 1 or 3) pv; f3 with av and pv shorter and fewer than in male; t3 with 1-3 (usually 2) av, 4 (rarely 5) ad, 3 (rarely 4) pd and 1-2 (none in 1 specimen) pv.